1. Field of the Invention
The present invention relates in general to electric lamp assemblies and more particularly to electric lamp assemblies of a type which comprises a bulb unit and a base structure of moulded plastics.
2. Description of the Prior Art
Prior to describing in detail the present invention, one of the conventional electric lamp assemblies will be outlined with reference to FIG. 35 in order to clarify the task of the invention.
Referring to FIG. 35, there is shown a conventional electric lamp assembly "a" which is disclosed in U.S. Pat. No. 4,412,273. The electric lamp assembly "a" comprises a rounded base structure "b" of moulded plastics having a smaller diameter rear portion from which terminals "c" are projected outward. A metal sleeve "d" is coaxially disposed on and secured to a front portion of the base structure "b". The metal sleeve "d" is formed at its leading end with small spaced lugs "e" which are welded to cylindrical outer surface of a circular metal cap "f". The metal cap "f" is snugly disposed at its rear end in the mouth portion of the metal sleeve "d" and supports thereon a bulb "g". The bulb "g" has therein a filament "h" from which lead wires (not shown) extend to the outside of the bulb "g". Although not shown in the drawing, the lead wires are welded to inward projected ends of the terminals "c" within the metal sleeve "d".
However, due to its inherent construction, the electric lamp assembly "a" has the following drawbacks.
First, it is troublesome to properly connect the lead wires to the terminals "c" in the metal sleeve "d". That is, during assembly, the lead wires from the bulb "g" are welded to the inward projected ends of the terminals "c" held by the base structure "b", and the metal sleeve "d" is put on the front portion of the base structure "g" having the bulb "b" and the metal cap "f" passed therethrough, and the metal sleeve "d" is secured to the base structure "b" and then, the metal cap "f" is turned about its axis to a given angular position relative to the base structure "b" and thereafter, the small lugs "e" of the metal sleeve "d" are welded to the metal cap "f". However, this assembling procedure tends to induce an undesirable short circuit of the lead wires with the metal sleeve "d" particularly when the lead wires have remained relatively long within length in the metal sleeve "d". In fact, by the presence of the metal sleeve "d", the condition of the connections of the lead wires can not be viewed from the outside of the assembly "a".
Second, it is difficult to properly set the angular position of the bulb "g", viz., the filament "h" of the same relative position to the base structure "b". Because of absence of any positioning means between the metal sleeve "d" and the metal cap "f", the angular positioning of the bulb "g" must be made roughly depending on the assembling techniques individually possessed by assemblers.